Vacuum concentrator for juices or the like



May 27, 1958 M. M. KOFFLER 2,836,235 VACUUM CONCENTRATOR FOR JUICES OR THE LIKE 2 Sheets-Sheet 1 Filed Jan. 10, 1956 INVENTOR MAXIMILIAN KOFFLER ATTORNEYS VACUUM CONCENTRATOR FOR JUICES OR THE LIKE Filled Jan. 10, 1956 May 27, 1958 M. M. ,KOFFLER 2 Sheets-Sheet 2 Mil/iii? INVENTOR MAXIMILIAN HOFFLER E BY WM ATTORNEYS VACUUM CONCENTRATQR FGR JUICES GK THE LIKE 'M. Kofiler, Tel Aviv, lsrael Claims priority, application Israel July 15, F955 1 Claim. (Cl. 1596) Application .ianuary 1t), 1956, Serial No.

This invention relates to a vacuum concentrator for number of upright heat exchanging surfaces of circular 21-1 cross-section disposed 'coaxially within each other, the first one forming the inner wall of an outermost heat exchanger, the other forming the outer and inner walls, respectively, of coaxial inner heat exchangers, and

means for producing the flow of the liquid as a thin film 1) in succession down the first surface, and up and down the outer and inner surfaces of the inner heat exchangers, toward the bottom Zone of the inner surface of the innermost heat exchanger.

The inner heating surfaces of the heat exchangers may slope toward their axis so that the/downward flow of the liquid is slowed down alo'ng'these heating surfaces.

It is preferred to provide substantially radial blades revolving about the axis of the concentrator and having their outer edges disposed parallel'to the inner heating surfaces of the heat exchangers at a small'distance thereflom. These blades serve on the one hand to throw the liquid, fed into the top part of the concentrator, centrifugally towards the inner heating surface of the outer heat motion which is preferably rectified by baffles or the like in the transition between the heatexchangers.

While the liquid flows by gravity down the inner heating surfaces of the'heat exchangers, its fiow up the outer heating surfaces of the inner heat exchangers must be produced positively. Bya particular feature of the invention this may be doneby means of a rotating sleeve surrounding the innerheat exchanger or one such sleeve for each inner heat exchanger, and dipping with its bot tom edge into the liquid collecting at the bottom'of the inner surface of'the preceding heat exchanger, "e. g. in a trough there located. This sleeve is provided on its inner face with vanes imparting to the liquid a spiral upward movement by centrifugal action. The vanes need not extend over the full height of the sleeve but may be confined to the bottom zone thereof.

Of course, other pumping means may be used instead, e. g. piston pumps so disposed as to deliver the liquid in upward direction along the outer surfaces of the inner heat exchanger.

Bafiies similar to those provided in the transition between the heat exchangers may also be disposed on the top of the inner heat exchangers in order to right the Because of this fact, the

United rates itatent Lil ' Patented MayZi', 1953 ice flow of the liquid before this starts flowing down along the inner surfaces of the inner heat exchangers. Both groups of bafiies are suitably disposed in radial positions, or at small angles from the radii of the concentrator.

Where the concentrator according to the invention is used for single-stage operation, it is provided with a conventional hood which is connected to a vacuum duct and which may enclose foam bafl'les or the like means preventing liquid to be carried oh by the escaping vapours. Where the apparatus is used as a second-stage concentrator it may be mounted directly at the bottom end of the first-stage concentrator.

The invention is illustrated, by way of example only, in the accompanying drawings in which:

Fig. l is an axial section of a vacuum concentrator according to the invention;

Fig. 2 is a horizontal section thereof on line lI--il;

Fig. 3 shows a detail of Fig. l in vertical section on a larger scale;

Fig. 4 is a detail in evolution;

Fig. 5 is a horizontal section on line V-V of Fig. l.

The concentrator here illustrated comprises a heat exchanger 1 of inverted 'frustoconical shape disposed within a jacket 2 of similar shape. The upper part 3 of the heat exchanger 1 is substantially cylindrical and projects upwards out of the jacket 2. its flanged upper edge 3 is secured to the bottom flange 4 of a cylindrical body 5 Which may be either ahood connected to a vacuum duct, or the bottom part of another concentrator in which a first concentrating stageis performed and to which the concentrator according to the invention is co nected in cascade. The connection between the heat exchanger and the hood or other concentrator 5 may be modified in any suitable manner, and in particular the heat exchanger may be hingedly connected to the body 4 so that it can be swung open. The bottom end of the heat exchanger '1 merges through the bottom into an annular trough 7 below the bottom 6 of the concentrator. This bottom 6 in its turn merges into the jacket 2. The trough is covered by an annular lid 8 extending over a part of the width of the trough.

Co-axially disposed within the heat exchanger 1 is a second heat exchanger 9 which is also secured to the bottom 6 of the concentrator. This is an annular body of about trapezoidal cross section whose outer'side it? and inner side 11 both "serve as heat exchanging surfaces. The outer side 19 is substantially vertical and merges into the trough 7. The innerside l1 slants downwards into a vpit 12. The inner wall 'of the pit 12 is formed by a cylindrical body 15 whose top wall 14 has a central aperture.

Within the trough 7 there are disposed at number of baffles 15 which may be substantially radial or include relatively small angles with the radii. These serve for rectifying the how of-the liquid which flows down along the inner-side of the outer heat exchanger 1 and in doing so is also given a circumferential motion. Similarly, a number of bafiies 16 are disposed'in radial or radial positions-on the'top'of the inner heat exchanger The jacket space surrounding theouter heat exchanger has an inlet 17 and outlet 18 for a heating fluid, e. g. steam under pressure. A similar inlet and outlet (not shown) are provided for the inner heat exchanger 9. The latter may be connected in series with the outer heat exchanger, or it may be supplied with heating fluid independently of therlatter.

To the pit 12 an outlet 19 with control valve 21? is connected. A refractometer 21 is provided in the outlet 19. Its indications are a measure of the degree of concentration of the outgoing liquid. If this is not yet sufficiently concentrated it can be recycled into the concen trator.

A shaft 22 is journalled in suitable bearings of which one is disposed in a plate 23 at the bottom of a pit 24 joined to the bottom 6 oflthe apparatus, while at least one other bearing is disposed at any suitable Place above or below the former, e; g. in'the top wall 14 of the cylindrical body 13. The shaft is rotated by a motor 25 whose shaft 26 is connected to a pulley 27 on shaft 22 by a transmission belt 28.

In the chamber within the cylindrical part ,3. of the heat exchanger 1, a hub 29 is keyed on shaft 22; This hub carries a distribution plate 30, a number of radial blades 31-eight in this exampleand an annular distribution plate32.

Beneath the hub 29, another hub 33 is keyed on shaft '22. This carries a. number of radial blades 34+four 'mm. or even less.

Immediately below the hub 33, radial arms or spikes 36 are secured to a hub 36' keyed to the shaft 22." To their ends there is fixed the upper, inwards rimmed edge 37 of a sleeve 38 which surrounds the: inner heat exchanger 9. The bottom edge of the sleeve. 38 dips into the Vtrough-7 past the lid S'of the latter and carrieson its. inner face a plurality of vanes 39. These vanes are slightly curved, as shown in Fig. 4. The sleeve 38 serves 7 as a centrifugal pump which, by means of the vanes 39,

takes up the liquid collecting in the trough 7 and delivers it upwards along the outer face of the heat exchanger 9 and past the top of the latter. The sleeve38is structurally reinforced by outer annular ribs or flanges 40 which also serve for the support of radial blades 41.; The

;- 2,836,235 I A y a r '4 changer 9. On reaching the top it is directed inwards by the rim 37 of the sleeve 38, and its flow is straightened by the baffles 16. Thereafter it descends in a straight and quiet flow along theinner surface 11 of the inner heat exchanger, in order finally to collect in the pit 12 whence it is drained off through the conduit'19.-

Where a higher numberof heat exchangers is provided,

say three, with altogether five heat exchanging surfaces,

the general design of the blades and rotary sleeves may be analogous with still higher numbers of heat exchangers, the mechanical difiiculties become so great as to outweigh the advantages.

The concentrator according to the invention has been '7 others form the outer and inner wall, respectively, Of an inner heat exchanger; means for substantially uniformly distributing liquid to be concentrated over the'top zone is of the outermost heat exchanging surface; an annular trough in the bottom region between the two heat exchangers for collecting the liquidflowing off the outermost heat exchanging surface, artrough for collecting the concentrate flowing off the innermost heat exchanging surface, and means for withdrawing the concentrate from this collecting trough; substantially radial bladesmounted on a rotary shaft disposed in the axis 'of the heat exlatter are in vertical register with the outer. parts of. 7

blades 34, and their outer edges are continuations of those of blades34. V Below the arms 36 another hub .42 is keyed on the shaft 22. This carries radial blades'43 in vertical register with which is centrifugally thrown towards the surface 3; The

part of the liquid which does not reach the wall 3 drops onto the'plate 32 and is delivered to the surface 3 by the revolving plate 32 in cooperation of the blades 31.

The liquid flows down along the surfaces 3 andl and is heated indirectly by the heating fluid streaming through a the jacket space 2. As the liquid flows down itisreduced to a'thin film bythe blades 34 and'41 Which'act both as fans and as scrapers; Theblades' impart 'to the liquid a lateral motion. When the liquid reaches the trough 7, the sideward component of its movement is suppressed by the bafiies 15.

I From the trough 7, the liquid'is taken up byrthe vanes changers with their outer edges parallel to the inner surfaces of both heat exchangers, respectively, at a small distance therefrom, and being adapted to move peripherally and to reduce to a thin film the liquid layer flowing down along these surfaces; a cylindricalsleeve secured to said shaft, said sleeve being rimmed inwards and open at its top {and surroundingthe inner. heat exchanger at a small distance therefrom and having on its inner surface, within said annular trough, vanes adapted to take. up the liquid pressing peripheral movement thereofmanta Cited n the file of this patent;

M e UNITED STATES PATENTS 538,556 Theisen j Apr; '3, 1895 557,993 Kortumv ,Apr. 7,1896

734,228 Gerber July 21,1903 1,888,872 Yarmet a Nov, 22, 1932 2,455,059 Hickman Nov. 30, 1948 2,561,395 Marshall July 24, 1951 2,774,415 Belcher Dec. 18 1956 FOREIGN PATENTS 6,816 Norway May 14, 1898 500,400

Great Britain e Feb. 8, 1939 

